1. Field of the Invention
The present invention relates generally to machine gun mounts and, more particularly, to traverse and elevation mechanisms for machine gun mounts.
2. Description of Related Art
A machine gun fired from a tripod can be held in place by a mechanical device, which is commonly referred to as a traverse and elevation mechanism. A typical traverse and elevation design consists of a vertical arm of variable length which travels along a horizontal (traverse) bar. The mechanical linkage and components required for this type of mechanism subject the design to problems and limitations relating to functionality and performance. One purpose of a traverse and elevation mechanism is to hold the weapon steady in a position chosen by the gunner and to provide adjustments to the chosen position. Prior art traverse and elevation mechanisms generally suffer from poor target acquisition time, operational complexity, backlash, and loose parts.
Target acquisition time refers to the time required by a user to acquire a target. This time is typically slow because of the complex nature of operation required by conventional traverse and elevation mechanisms. Adjustments in weapon aiming position are restricted by the physical limits of the prior art mechanical traverse and elevation mechanisms. Coarse adjustments are only allowed in traverse, and are accomplished by physically moving the traverse and elevation mechanism on it's support bar. The use of both of a user's hands is required to first release a traverse and elevation mechanism clamp, simultaneously move both the weapon and the traverse and elevation mechanism to a desired configuration, and finally re-secure the clamp in the desired position, all of which can be cumbersome and time consuming in a battle situation.
Fine adjustments in both traverse and elevation are provided by movement of the traverse and elevation mechanism itself. Adjustments are made by rotating a detented knob which provides a preset amount of rotation between detents. Rotation of the adjustment knob is translated into small changes in traverse and/or elevation. The actual change in the traverse and elevation mechanism setting, by using the adjustment knob detents, may or may not provide the change in setting desired by the gunner. For example, a one detent change in azimuth may be too little and a second detent change may be too much. Also, clearances, commonly referred to as backlash, between the rotating elements of the adjusting mechanism can cause additional aiming errors.
Tolerances between the mechanical parts of traverse and elevation mechanisms introduces working clearances. These working clearances can permit small movements of the weapon which cause large errors in the impact area of the projectiles at extended ranges.
In summary, the problems with prior-art traverse and elevation mechanisms are as follows: (1) coarse adjustments require the use of both hands, are time consuming, and are allowed only in the traverse direction; (2) fine adjustments are sometimes not fine enough to point the weapon exactly at the desired target; and (3) clearances between the traverse and elevation mechanism parts introduce aiming errors and can allow for too much unintended movement of the weapon.
Regarding operational complexity, in many cases the operator must take his or her eyes off of the target and his or her hand off of the weapon to operate the traverse and elevation mechanism. Also, course adjustments and fine adjustments are entirely different procedures, which adds to the complexity of the task. In the case of a fine adjustment, it is possible to run out of fine adjustment travel, requiring the operator to make an additional course adjustment before acquiring the target.
Additionally, regarding the problem of backlash associated with prior art traverse and elevation mechanisms, because of the mechanical linkage involved, it is almost impossible to eliminate backlash from these systems. This phenomena can result in inaccuracy. It is therefore usually required that the operator bias the weapon in a certain direction when aiming and when firing. This limitation leads to inaccuracy. Further, prior art traverse and elevation systems generally comprise a number of loose parts. In most installations, when the weapon is removed from the traverse and elevation mechanism mount and the traverse and elevation mechanism mount is stored, the traverse and elevation mechanism is an extra or loose part. This arrangement can prove to be inconvenient in an infantry situation.